1. Field of Invention
The present invention relates to a method for processing a film. More particularly, the present invention relates to a method for forming protuberant structures on the film.
2. Description of Related Art
A typical metal material is commonly used because of its special luster. For example, a signboard or a billboard for decorating is surface finished with metal and is shaped by computerized cutting to attract people's attention. Sometimes the metal is processed by special treatment to produce different feeling of sight and touch. An example of special treatment is the sandblasting treatment used to form fine grains on the surface of the metal to make different reflections and refraction of light, so that the different feelings of beauty can be produced.
However, it is hard to control the surface feature of the metal when using the sandblasting treatment. Furthermore, this sandblasting treatment causes poor uniformity and lower reproducibility, is time-consuming and manpower consuming, and the hardware of the sandblasting is quite expensive. Therefore, the sandblasting treatment has its restrictions and is not suitable for circumstances, which requires high throughput, fineness, high-quality reproduction and good uniformity.